High performance, flexible, and compact low-density parity-check (LDPC) code

Abstract

Certain aspects of the present disclosure generally relate to techniques for puncturing of structured low-density parity-check (LDPC) codes. Certain aspects of the present disclosure generally relate to methods and apparatus for a high-performance, flexible, and compact LDPC code. Certain aspects can enable LDPC code designs to support large ranges of rates, blocklengths, and granularity, while being capable of fine incremental redundancy hybrid automatic repeat request (IR-HARQ) extension while maintaining good floor performance, a high-level of parallelism to deliver high throughout performance, and a low description complexity.

What is claimed is: 
     
       1. A method for wireless communication, comprising:
 determining a low-density parity-check (LDPC) base graph associated with a plurality of LDPC codes for a plurality of code rates and blocklengths, the LDPC base graph having a number of base graph columns corresponding to a maximum number of information bits; 
 determining a lifting size value for generating a lifted LDPC parity check matrix (PCM); 
 generating the lifted LDPC PCM based on the LDPC base graph and the lifting size value; and 
 generating an LDPC code based on the lifted LDPC PCM and an all zero vector, wherein the LDPC code was shortened by either (i) removing one or more of the base graph columns or (ii) removing one or more lifted LDPC PCM columns, and wherein the shortening was based on at least one of: a code rate, a lifting size value, or a blocklength for a transmission. 
 
     
     
       2. The method of  claim 1 , wherein the determining the lifting size value for generating the lifted LDPC PCM determines a number of the one or more base graph columns or the one or more lifted LDPC PCM columns removed to shorten the LDPC code. 
     
     
       3. The method of  claim 1 , further comprising:
 encoding the transmission using the LDPC code; and 
 transmitting the LDPC code encoded transmission over a wireless channel. 
 
     
     
       4. The method of  claim 3 , wherein the transmission comprises a physical uplink shared channel (PUSCH) transmission or a physical downlink shared channel (PDSCH) transmission. 
     
     
       5. The method of  claim 1 , wherein the plurality of LDPC codes are associated with different numbers of base graph columns, equal to or less than the number of base graph columns corresponding to the maximum number of information bits. 
     
     
       6. The method of  claim 1 , further comprising setting bits corresponding to the removed one or more of the base graph columns or the removed one or more lifted LDPC PCM columns to zero. 
     
     
       7. The method of  claim 1 , wherein determining the lifting size value comprises:
 selecting the lifting size value such that a ratio of a number of a set of information bits to the lifting size value is equal to or less than the maximum number of information bits. 
 
     
     
       8. The method of  claim 7 , wherein the selecting comprises selecting a smallest lifting size value from a set of supported lifting size values. 
     
     
       9. The method of  claim 1 , wherein:
 the LDPC base graph comprises a core graph including a number of information bit columns and a number of parity bit columns; and 
 generating the LDPC code includes determining an LDPC extended graph by adding to the core graph one or more extended parity bit columns based on a number of information bits to be encoded and the blocklength. 
 
     
     
       10. The method of  claim 9 , wherein:
 the information bit columns of the core graph are degree 2 or higher; 
 the one or more extended parity bit columns are formed by a parity of one or more of the information bit columns or one or more of the parity bit columns; and 
 the LPDC base graph includes:
 two punctured highest-degree variable nodes; 
 an additional one-degree parity bit formed by a parity of the two punctured highest-degree variable nodes; and 
 a plurality of LDPC base graph rows corresponding to check nodes. 
 
 
     
     
       11. The method of  claim 9 , wherein:
 the information bit columns of the core graph are degree 3 or higher; 
 the one or more extended parity bit columns are formed by a parity of one or more of the information or one or more of the parity bit columns; and 
 the LDPC base graph includes a plurality of LDPC base graph rows corresponding to check nodes. 
 
     
     
       12. An apparatus for wireless communication, comprising:
 at least one processor; and 
 a memory coupled to the at least one processor, the memory comprising code executable by the at least one processor to cause the apparatus to:
 determine a low-density parity-check (LDPC) base graph associated with a plurality of LDPC codes for a plurality of code rates and blocklengths, the LDPC base graph having a number of base graph columns corresponding to a maximum number of information bits; 
 determine a lifting size value for generating a lifted LDPC parity check matrix (PCM); 
 generate a lifted LDPC PCM based on the LDPC base graph and the lifting size value; and 
 generate an LDPC code based on the lifted LDPC PCM and an all zero vector, wherein the LDPC code was shortened by either (i) removing one or more of the base graph columns or (ii) removing one or more lifted LDPC PCM columns, and wherein the shortening was based on at least one of: a code rate, a lifting size value, or a blocklength for a transmission. 
 
 
     
     
       13. The apparatus of  claim 12 , wherein the code executable by the at least one processor to cause the apparatus to determine the lifting size value for generating the lifted LDPC PCM determines a number of the one or more base graph columns or the one or more lifted LDPC PCM columns removed to shorten the LDPC code. 
     
     
       14. The apparatus of  claim 12 , further comprising code executable by the at least one processor to cause the apparatus to:
 encode the transmission using the LDPC code; and 
 transmit the LDPC code encoded transmission over a wireless channel. 
 
     
     
       15. The apparatus of  claim 14 , wherein the transmission comprises a physical uplink shared channel (PUSCH) transmission or a physical downlink shared channel (PDSCH) transmission. 
     
     
       16. The apparatus of  claim 12 , wherein the plurality of LDPC codes are associated with different numbers of base graph columns, equal to or less than the number of base graph columns corresponding to the maximum number of information bits. 
     
     
       17. The apparatus of  claim 12 , further comprising code executable by the at least one processor to cause the apparatus to set bits corresponding to the removed one or more of the base graph columns or the removed one or more lifted LDPC PCM columns to zero. 
     
     
       18. The apparatus of  claim 12 , wherein the code executable by the at least one processor to cause the apparatus to determine the lifting size value comprises code executable by the at least one processor to cause the apparatus to select the lifting size value such that a ratio of a number of a set of information bits to the lifting size value is equal to or less than the maximum number of information bits. 
     
     
       19. The apparatus of  claim 18 , wherein the code executable by the at least one processor to cause the apparatus to select comprises code executable by the at least one processor to cause the apparatus to select a smallest lifting size value from a set of supported lifting size values. 
     
     
       20. The apparatus of  claim 12 , wherein the LDPC base graph comprises:
 a core graph including a number of information bit columns and a number of parity bit columns; and 
 the code executable by the at least one processor to cause the apparatus to generate the LDPC code includes code executable by the at least one processor to cause the apparatus to determine an LDPC extended graph by adding to the core graph one or more extended parity bit columns based on a number of information bits to be encoded and the blocklength. 
 
     
     
       21. The apparatus of  claim 20 , wherein:
 the information bit columns of the core graph are degree 2 or higher; 
 the one or more extended parity bit columns are formed by a parity of one or more of the information bit columns or one or more of the parity bit columns; and 
 the LPDC base graph includes:
 two punctured highest-degree variable nodes; 
 an additional one-degree parity bit formed by a parity of the two punctured highest-degree variable nodes; and 
 a plurality of LDPC base graph rows corresponding to check nodes. 
 
 
     
     
       22. The apparatus of  claim 20 , wherein:
 the information bit columns of the core graph are degree 3 or higher; 
 the one or more extended parity bit columns are formed by a parity of one or more of the information or one or more of the parity bit columns; and 
 the LDPC base graph includes a plurality of LDPC base graph rows corresponding to check nodes. 
 
     
     
       23. A method for wireless communication, comprising:
 receiving a low-density parity-check (LDPC) code; 
 determining a lifting size value for a lifted LDPC parity check matrix (PCM); and 
 determining an LDPC base graph associated with the LDPC code and the lifted LDPC PCM, the LDPC base graph having a number of base graph columns corresponding to a maximum number of information bits, wherein the LDPC code was shortened by either (i) removing one or more of the base graph columns or (ii) removing one or more lifted LDPC PCM columns, and wherein the shortening was based on at least one of: a code rate, a lifting size value, or a blocklength for transmission. 
 
     
     
       24. The method of  claim 23 , wherein the determining the lifting size value for the lifted LDPC PCM determines a number of the one or more base graph columns or the one or more lifted LDPC PCM columns removed to shorten the LDPC code. 
     
     
       25. The method of  claim 23 , further comprising:
 receiving the transmission over a wireless channel; and 
 decoding the transmission to receive the LDPC code. 
 
     
     
       26. The method of  claim 23 , wherein the LDPC base graph is associated with a plurality of shortened LDPC codes for a plurality of code rates and blocklengths, and wherein the plurality of shortened LDPC codes are associated with different numbers of base graph columns, equal to or less than the number of base graph columns corresponding to the maximum number of information bits. 
     
     
       27. An apparatus for wireless communication, comprising:
 at least one processor; and 
 a memory coupled to the at least one processor, the memory comprising code executable by the at least one processor to cause the apparatus to:
 receive a low-density parity-check (LDPC) code; 
 determine a lifting size value for a lifted LDPC parity check matrix (PCM); and 
 determine an LDPC base graph associated with the LDPC code and the lifted LDPC PCM, the LDPC base graph having a number of base graph columns corresponding to a maximum number of information bits, wherein the LDPC code was shortened by either (i) removing one or more of the base graph columns or (ii) removing one or more lifted LDPC PCM columns, and wherein the shortening was based on at least one of: a code rate, a lifting size value, or a blocklength for transmission. 
 
 
     
     
       28. The apparatus of  claim 27 , wherein code executable by the at least one processor to cause the apparatus to determine the lifting size value for the lifted LDPC PCM determines a number of the one or more base graph columns or the one or more lifted LDPC PCM columns removed to shorten the LDPC code. 
     
     
       29. The apparatus of  claim 27 , further comprising code executable by the at least one processor to cause the apparatus to:
 receive the transmission over a wireless channel; and 
 decode the transmission to receive the LDPC code. 
 
     
     
       30. The apparatus of  claim 27 , wherein the LDPC base graph is associated with a plurality of shortened LDPC codes for a plurality of code rates and blocklengths, and wherein the plurality of shortened LDPC codes are associated with different numbers of base graph columns, equal to or less than the number of base graph columns corresponding to the maximum number of information bits. 
     
     
       31. An apparatus for wireless communication, comprising:
 encoder circuitry configured to:
 obtain a set of information bits; 
 determine a low-density parity-check (LDPC) base graph associated with a plurality of LDPC codes for a plurality of code rates and blocklengths, the LDPC base graph having a number of base graph columns corresponding to a maximum number of information bits; 
 determine a lifting size value for generating a lifted LDPC parity check matrix (PCM); 
 generate a lifted LDPC PCM based on the LDPC base graph and the lifting size value; 
 generate a shortened LDPC code based on the lifted LDPC PCM by removing one or more of the base graph columns, wherein the shortening is based on at least one of: a code rate, a lifting size value, or a blocklength for a transmission; and 
 encode the set of information bits using the LDPC code; and 
 
 transmitter circuitry configured to transmit the encoded set of information bits via one or more antennas over a wireless medium. 
 
     
     
       32. The apparatus of  claim 31 , wherein the encoder circuitry is configured to:
 select the lifting size value such that a ratio of a number of a set of information bits to the lifting size value is equal to or less than the maximum number of information bits. 
 
     
     
       33. The apparatus of  claim 31 , wherein the transmission comprises a physical uplink shared channel (PUSCH) transmission or a physical downlink shared channel (PDSCH) transmission. 
     
     
       34. The apparatus of  claim 31 , wherein:
 the LDPC base graph comprises a core graph including a number of information bit columns and a number of parity bit columns; and 
 the encoder circuitry is configured to determine an LDPC extended graph by adding to the core graph one or more extended parity bit columns based on a number of information bits to be encoded and the blocklength. 
 
     
     
       35. An apparatus for wireless communication, comprising:
 receiver circuitry configured to receive, via one or more antennas over a wireless medium, a set of low-density parity-check (LDPC) code encoded bits; and 
 decoder circuitry configured to:
 determine a lifting size value for a lifted LDPC parity check matrix (PCM); and 
 determine an LDPC base graph associated with the LDPC code and the lifted LDPC PCM, the LDPC base graph having a number of base graph columns corresponding to a maximum number of information bits, wherein the LDPC code was shortened by removing one or more of the base graph columns, and wherein the shortening was based on at least one of: a code rate, a lifting size value, or a blocklength for transmission; and 
 decode the set of LDPC code encoded bits with the LDPC base graph to obtain a set of one or more information bits. 
 
 
     
     
       36. The apparatus of  claim 35 , wherein the decoder circuitry is configured to:
 select the lifting size value such that a ratio of a number of a set of information bits to the lifting size value is equal to or less than the maximum number of information bits. 
 
     
     
       37. The apparatus of  claim 35 , wherein the transmission comprises a physical uplink shared channel (PUSCH) transmission or a physical downlink shared channel (PDSCH) transmission. 
     
     
       38. The apparatus of  claim 35 , wherein:
 the LDPC base graph comprises a core graph including a number of information bit columns and a number of parity bit columns; and 
 the decoder circuitry is configured to determine an LDPC extended graph by adding to the core graph one or more extended parity bit columns based on a number of information bits to be encoded and the blocklength.